Abstract

Deep-seismic reflection profiles across parts of the Central Appalachian orogenic belt indicate that the crust here includes an exposed Paleozoic fold- and-thrust belt that is mainly soled in Proterozoic Grenville basement. Translation strain in the foreland and Highlands resulting from Paleozoic orogenesis is as much as 25 km, exclusive of layer-parallel-shortening penetrative strains. This estimate is limited by the slight structural relief beneath the Pocono plateau and by the lack of extensive Cambrian-Ordovician cover beneath the sole thrust. Earlier estimates of translation strain are much higher. To the southwest, this parautochthonous region is separated by an unrecognized structural transition from the more afochthonous parts of the central and southern Appalachian overthrust belt, marked by significantly larger translation strains. Crustal architecture in the hinterland part of the region is poorly understood due to data gaps.

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